The Pediatric Oncology Group (POG) is a multi-disciplinary, multi- institutional research community dedicated to finding better treatments for childhood cancer and leukemia. McGill University, a POG founding member, requests support to continue to contribute to all aspects of POG biologic, therapeutic, epidemiologic and evaluative clinical cancer research for the next 5 years. We will enroll the maximum number of patients into multi-modality therapeutic studies of childhood leukemias, lymphomas, solid tumors, and brain tumors; and into non-therapeutic studies of cancer etiology, epidemiology, biology, and late effects of therapy. We are recruiting a satellite, the University of Ottawa, to increase patient accrual, particularly patients with brain tumors. We will comply with IRB ethical requirements and NCI requirements for toxicity reporting and control of restricted drugs. We will continue to participate actively in the administrative, educational and scientific activities of the POG. McGill investigators will continue to contribute to POG science. Acute lymphoblastic leukemia (ALL): Dr. Whitehead has studied tissue delivery of anti-leukemic drugs in two frontline ALL protocols (ALinC 14 and 15). He will test the hypothesis that extent of metabolism of methotrexate in lymphoblasts at diagnosis influences event-free survival in ALL in ALinC 15. New agents and pharmacology: Drs. Bernstein and Whitehead are coordinating a study of Ifosphamide and VP-16 in leukemia (phase I). They will coordinate two phase I studies of Fazarabine in leukemia and in solid tumors. Neuro-oncology: Dr. Freeman will continue to study hyperfractionated radiation therapy in brain stem gliomas. Dr. Baruchel will conduct a phase I study of Acivicin in brain tumors. The University of Ottawa will concentrate initially on the study of brain tumors. Bone marrow transplantation (BMT): Government funding for 4 BMT beds will allow Dr. Koch to enroll many more patients on POG BMT protocols. HIV infection: Dr. Baruchel initiated and is a member of an ad hoc committee to study HIV-associated lymphoma in POG. Neuroblastoma: Dr. Bernstein formed a collaborative group; including POG, to determine whether neuroblastoma can be detected early by screening Quebec newborns for elevated urinary catecholamines. All Quebec children with neuroblastoma, diagnosed clinically or pre-clinically, will be enrolled on POG protocols.